The present invention relates to thermowells, and in particular, to thermowell vibration.
Thermowells are used in the process control industry to house temperature sensors. A thermowell is typically a long, cylindrical tube that is sealed at one end and open at the other end. The temperature sensor is inserted in the open end of the thermowell and the thermowell is inserted into a process fluid. This arrangement allows the temperature sensor to measure temperature of the process fluid without being directly exposed to the process fluid. This can be helpful to protect the temperature sensor when the process fluid is hazardous to the temperature sensor.
In many applications, the thermowell is inserted in a process where the process fluid flows over and around the thermowell. This can cause turbulence, eddies, and vortices, which can cause the thermowell to vibrate. In certain circumstances, such vibrations can cause the thermowell to oscillate at its natural frequency. Oscillation at the thermowell's natural frequency can cause the thermowell to fail from fatigue, ultimately cracking or even breaking off. Such failure can cause the temperature sensor to fail and the entire process to require shut-down. In some processes, any breach in a process barrier such as thermowell failure can cause fires, environmental damage, or other hazardous situations.